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Journal of Chemical Sciences

, 130:134 | Cite as

Self-assembly and photoinduced electron transfer in a donor- \(\upbeta \)-cyclodextrin-acceptor supramolecular system\(^{\S }\)

  • Retheesh Krishnan
  • Sumesh Babu Krishnan
  • Bijitha Balan
  • Karical Raman Gopidas
Regular Article
  • 127 Downloads

Abstract

Equimolar amounts of native \(\upbeta \)-cyclodextrin (\({\varvec{\upbeta }}\)-CD), pyrene-linked adamantane (PYAD) and tert-butylpyromellitic diimide (PMDI) when dissolved in water self-assembled to form the supramolecular donor-acceptor system \(\mathbf{PYAD}{\sqsupset }{\varvec{\upbeta }}\)-\(\mathbf{CD}{\succ }\mathbf{PMDI}\). The high affinity of adamantane derivatives for inclusion binding in the \({\varvec{\upbeta }}\)-CD cavity and the propensity of PMDI to undergo rim-binding at the narrow rim of \(\upbeta \)-CD led to the formation of \(\mathbf{PYAD}{\sqsupset }{\varvec{\upbeta }}\)-\(\mathbf{CD}{\succ }{} \mathbf{PMDI}\). The ternary complex \(\mathbf{PYAD}{\sqsupset }{\varvec{\upbeta }}\)-\(\mathbf{CD}{\succ }{} \mathbf{PMDI}\) was thoroughly characterized using various spectroscopic techniques. \(\upbeta \)-CD performs three functions in the self-assembled complex: (1) encapsulate the adamantane unit and keep the pyrene (PY) moiety above the secondary rim, (2) rim-bind PMDI and keep it at the primary rim, and (3) act as a spacer between pyrene and PMDI. Thus, the ternary complex can function as a donor-spacer-acceptor system capable of undergoing photoinduced electron transfer (PET). Upon excitation of the pyrene moiety in \(\mathbf{PYAD}{\sqsupset }{\varvec{\upbeta }}\)-\(\mathbf{CD}{\succ }{} \mathbf{PMDI}\) an electron is transferred from the excited pyrene to the PMDI ground state. Steady state and time resolved fluorescence experiments were carried out to study the PET in \(\mathbf{PYAD}{\sqsupset }{\varvec{\upbeta }}\)-\(\mathbf{CD}{\succ }{} \mathbf{PMDI}\). Existence of the ternary system and PET processes taking place within it are further supported by laser flash photolysis experiments.

Graphical abstract \(\upbeta \)-CD assembles donor pyrene through inclusion binding and acceptor pyromellitic diimide through rim-binding. Fluorescence intensity and lifetime quenching suggested photoinduced electron transfer from pyrene to pyromellitic diimide.

Keywords

Cyclodextrins donor–acceptor systems inclusion binding PET supramolecular assembly 

Notes

Acknowledgements

The authors thank DAE-BRNS (No. 2007/37/37/BRNS), and CSIR for financial support. R.K. and S. B. K. are grateful to CSIR for fellowships. This is contribution number NIIST-PPG 348.

Supplementary material

12039_2018_1535_MOESM1_ESM.pdf (1.4 mb)
Supplementary material 1 (pdf 1473 KB)

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Copyright information

© Indian Academy of Sciences 2018

Authors and Affiliations

  1. 1.Photosciences and Photonics, Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and TechnologyCouncil of Scientific and Industrial ResearchThiruvananthapuramIndia
  2. 2.Department of ChemistryGovernment College for WomenThiruvananthapuramIndia
  3. 3.Academy of Scientific and Innovative Research (AcSIR)New DelhiIndia
  4. 4.Department of ChemistryGovernment College KariavattomThiruvananthapuramIndia

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